Starting from a complete sample of type I AGN observed by INTEGRAL in the 20-40 keV band, we have selected a set of 8 AGN which can be classified as radio loud objects according to their 1.4 GHz power density, radio to hard X-ray flux flux density ratio and radio morphology. The sample contains 6 Broad Line Radio Galaxies and 2 candidate ones. Most of the objects in our sample display a double lobe morphology, both on small and large scales. For all the objects, we present broad-band (1-110 keV) spectral analysis using INTEGRAL observations together with archival XMM-Newton, Chandra, Swift/XRT and Swift/BAT data. We constrain the primary continuum (photon index and cut-off energy), intrinsic absorption and reprocessing features (iron line and reflection) in most of the objects. The sources analysed here show remarkable similarities to radio quiet type 1 AGN with respect to most of the parameters analysed; we only find marginal evidence for weaker reprocessing features in our objects compared to their radio quiet counterparts. Similarly we do not find any correlation between the spectral parameters studied and the source core dominance or radio to 20-100 keV flux density ratios, suggesting that what makes our objects radio loud has no effect on their high energy characteristics.
The bimodality of the AGN radio loudness distribution, and the relation of radio loudness and black hole mass were recently disputed. A closer look at the existing data suggests possible resolutions of these disputes, as further described below.
We revisit the issue of whether radio loudness in AGN is associated with central black hole mass, as has been suggested in the literature. We present new estimates of black hole mass for 295 AGN (mostly radio-quiet), calculating their radio loudnesses from published radio and optical fluxes, and combine with our previously published values, for a sample of 452 AGN for which both black hole mass and radio loudness (or upper limits thereto) are known. Among the radio-quiet AGN, there are now many black holes with mass larger than $10^{9}$ $M_{\odot}$, extending to the same high black hole masses…
In an examination of the relationship between the black hole mass and stellar velocity dispersion in radio-loud active galactic nuclei (AGNs), we studied two effects which may cause uncertainties in the black hole mass estimates of radio-loud AGNs: the relativistic beaming effect on the observed optical continuum radiation and the orientation effect on the broad emission line width. After correcting these two effects, we re-examined the relation between black hole mass and stellar velocity dispersion which derived from [OIII] line width for a sample of radio-loud and radio-quiet AGNs, and foun…
This erratum corrects a number of formulae containing mistakes in the paper 'Luminosity function, sizes and FR dichotomy of radio-loud AGN', 2007, MNRAS, v. 381, p.1548. The corrections do not alter any of the conclusions in the original paper.
A systematic difference in alignment between the central black hole spin and the angular momentum of the accreting gas may help explain several differences found in the optical and UV HST spectra of radio loud and radio quiet AGN.
We summarize the results of an X-ray spectroscopic survey of radio-loud AGNs observed with ASCA, using proprietary and archival data (public up to 1998 September). We briefly compare our results with those obtained for radio-quiet AGNs studied by other authors, and with the predictions of unified models.
The properties of the host galaxies of a well-defined sample of 2215 radio-loud AGN with redshifts 0.03 < z < 0.3, defined from the SDSS, are investigated. These are predominantly low radio luminosity sources, with 1.4GHz luminosities of 10^23 to 10^25 W/Hz. The fraction of galaxies that host radio-loud AGN with L(1.4GHz) > 10^23 W/Hz is a strong function of stellar mass, rising from nearly zero below a stellar mass of 10^10 Msun to more than 30% at 5x10^11 Msun. The integral radio luminosity function is derived in six ranges of stellar and black hole mass. Its shape is very similar in all of …
Because of the contamination of jets, using the size -- continuum luminosity relation can overestimate the broad line region (BLR) size and black hole mass for radio-loud AGNs. We propose a new relation between the BLR size and $H_β$ emission line luminosity and present evidences for using it to get more accurate black hole masses of radio-loud AGNs. For extremely radio-loud AGNs such as blazars with weak/absent emission lines, we suggest to use the fundamental plane relation of their elliptical host galaxies to estimate the central velocity dispersions and black hole masses, if their host gal…
The distribution of radio to optical fluxes in AGN is bimodal. The physical origin for this bimodality is not understood. In this Letter I describe observational evidence, based on the Boroson & Green PG quasar sample, that the radio loudness bimodality is strongly related to the black hole mass (M_BH). Nearly all PG quasars with M_BH>10^9M_sun are radio loud, while quasars with M_BH<3x10^8M_sun are practically all radio quiet. This result is consistent with the dependence of quasar host galaxy morphology on radio loudness. There is no simple physical explanation for this result, but it may pr…
Radio-loud AGN are characterized by relativistic jets originating near the central supermassive black hole and forming large-scale radio sources at parsec to kiloparsec to Megaparsec distances. The jets are energetically significant, in many cases representing the bulk of the energy extracted from the accretion process. Host galaxies are apparently normal luminous ellipticals, supporting the "Grand Unification" scenario wherein AGN are a transient phase in the evolution of every galaxy. Black hole mass appears to be largely uncorrelated with bolometric luminosity, Eddington ratio, radio lumino…
The International AGN Watch has monitored a number of radio-quiet and radio-loud Active Galactic Nuclei - the most luminous objects in the universe. We present a review of the main observational results from the continuum monitoring campaigns, concentrating on those which aim to quantify the simultaneous ultraviolet to X-ray variability characteristics. These data provide strong constraints on the proposed continuum emission mechanisms. The AGN Watch campaigns have made extensive use of a wide variety of both ground- and space-based multi-waveband observational facilities, and we stress that l…
Variability of 226 AGNs in the near-infrared $J$, $H$, and $K'$ bands is analyzed and discussed. An ensemble average for measured variabilities was obtained for various samples of the AGNs divided by absolute $B$-magnitude $M_B$, redshift $z$, and radio strength. All the samples in the $J$, $H$, and $K'$ bands are found to give significant ensemble variability, but no significant wavelength dependence is found. The ensemble variability in the entire sample combining the $J$, $H$, and $K'$ samples is $Δm\approx 0.22$ mag, while $Δm\approx 0.18$ mag for the radio-quiet AGNs and $Δm\approx 0.26$ …
In this review the correlations between host galaxy properties and black-hole mass determined from nearby quiescent galaxies are briefly discussed, before proceeding to investigate their application to active galactic nuclei (AGN). The recent advances in estimating the black-hole masses of AGN are then reviewed, followed by an examination of the connection between black-hole mass and radio luminosity.
[ABRIDGED] This is the third in a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. We selected 116 AGN candidates requiring a radio flux of 1 mJy. We classified the objects with HST images into ``core'' and ``power-law'' galaxies, on the basis of the nuclear slope of their brightness profiles. We used HST and Chandra data to isolate their nuclear emission to study the multiwavelength behaviour of their nuclei. The properties of the nuclei hosted by the 29 core galaxies were presen…
We report on the investigation of a complete sample of young radio-loud AGN at z<0.25, selected using the new comprehensive radio surveys and the optical APM/POSS-I catalog. This new sample will provide a unique opportunity for statistical studies of the early evolution of radio-loud AGN, free of cosmological evolution effects. In particular, their local luminosity function, linear-size and dynamical age distributions, may strongly constrain possible evolution scenarios. In addition, this new sample is well suited for statistical studies of other important properties, like their X-ray and infr…
After briefly summarizing the main tenets of unified schemes of Active Galactic Nuclei, I review some recent results in the field of unification of radio-loud sources, both for the low-luminosity (BL Lacs and Fanaroff-Riley type I radio galaxies) and high-luminosity (radio quasars and Fanaroff-Riley type II radio galaxies) populations.
We have discovered an obscured active galaxy at redshift z = 1.246 identified with the ROSAT X-ray source RX J1011.2+5545. We report on multiwavelength observations of this source and discuss its X-ray, optical and radio properties. This is the first X-ray selected, obscured active galaxy at high redshift to be shown to be radio-loud, with a radio counterpart exhibiting a classical double-lobe morphology.
By combining the 2-degree Field Galaxy Redshift Survey with the NRAO VLA Sky Survey at 1.4 GHz, the environments of radio loud AGN in the nearby Universe are investigated using both local projected galaxy densities and a friends-of-friends group finding algorithm. Radio-loud AGN are preferentially located in galaxy groups and poor-to-moderate richness galaxy clusters. The AGN fraction appears to depend more strongly on the large-scale environment (group, cluster, etc) in which a galaxy is located than on its more local environment, except at the lowest galaxy surface densities where practicall…
We present an X-ray spectral survey of radio-loud (RL) AGNs using ASCA and RXTE. The goal was to study the structure of their central engines and compare it to that of their radio-quiet (RQ) counterparts. We find Systematic differences in the X-ray properties of the two AGN classes. Specifically, RL AGNs exhibit weaker Fe lines and reflection components than RQ AGNs, indicating smaller solid angles subtended by the reprocessing medium to the X-ray source. The circumnuclear environs of RL and RQ AGNs also differ: large amounts of cold gas are detected in Broad Line Radio Galaxies and Quasars, c…
(Abridged) The prevalence of radio-loud AGN activity in present-day massive halos is determined using a sample of 625 nearby groups and clusters from the SDSS. Brightest group and cluster galaxies (BCGs) are more likely to host a radio-loud AGN than other galaxies of the same stellar mass (by less than a factor of two at a stellar mass of 5e11 M_sun, but over an order of magnitude below 1e11 M_sun). The distribution of radio luminosities for BCGs does not depend on stellar mass, however, and is similar to that of field galaxies of the same mass. Neither the radio-loud fraction nor the radio lu…
We present the results of a K-band imaging survey of 40 arcmin^{2} in fields around 14 radio-loud AGN (6 radio galaxies and 8 quasars) with z>1.5. The survey, 80% complete to K<19.2 and complemented by R-band imaging, aimed at investigating whether extremely red objects (EROs) are present in excess around high-z AGN, and to study the environment of z>1.5 radio galaxies and radio-loud quasars. At $18<K<19$ the differential galaxy counts in our fields suggest a systematic excess over the general field counts. At K<19.2, we find an excess of galaxies with R-K>6 compared to the general field. Cons…
We describe the dynamical evolution of hot spots velocity, pressure and mass density in radio loud active galactic nuclei (AGNs), taking proper account of (1) the conservations of the mass, momentum, and kinetic energy flux of the unshocked jet, (2) the deceleration process of the jet by shocks, and (3) the cocoon expansion without assuming the constant aspect ratio of the cocoon. By the detailed comparison with two dimensional relativistic hydrodynamic simulations, we show that our model well reproduces the whole evolution of relativistic jets. Our model can explain also the observational tre…
We compute two-point correlation functions and measure the shear signal due to galaxy-galaxy lensing for 80,000 optically identified and 5,700 radio-loud AGN from Data Release 4 (DR4) of the Sloan Digital Sky Survey. Halo occupation models are used to estimate halo masses and satellite fractions for these two types of AGN. The large sample size allows us to separate AGN according to the stellar mass of their host galaxies. We study how the halo masses of optical and radio AGN differ from those of the parent population at fixed M*. Halo masses deduced from clustering and from lensing agree sati…
We present the results of spectropolarimetry of a sample of 7 powerful radio galaxies and 2 quasars with $0.07<z<0.35$ obtained to detect possible anisotropies in the [OIII] line emission, which could explain the higher [OIII] luminosity of quasars than that of radio galaxies within the framework of the Unified Model of radio-loud AGN. We detect polarized [OIII] in 4 radio galaxies, consistent with the possibility that a considerable fraction ($\sim 20%$) of the observed [OIII] emission is scattered in a similar way to the hidden nuclear continuum. However, small but detectable rotation betwee…
The jet formation is thought to be closely connected with the mass of central supermassive black hole in Active Galactic Nuclei. The radio luminosity commonly used in investigating this issue is merely an indirect measure of the energy transported through the jets from the central engine, and severely Doppler boosted in core-dominated radio quasars. In this work, we investigate the relationship between the jet power and black hole mass, by estimating the jet power using extrapolated extended 151 MHz flux density from the VLA 5 GHz extended radio emission, for a sample of 146 radio loud quasars…
Nuclear jets containing relativistic ``hot'' particles close to the central engine cool dramatically by producing high energy radiation. The radiative dissipation is similar to the famous Compton drag acting upon ``cold'' thermal particles in a relativistic bulk flow. Highly relativistic protons induce anisotropic showers raining electromagnetic power down onto the putative accretion disk. Thus, the radiative signature of hot hadronic jets is x-ray irradiation of cold thermal matter. The synchrotron radio emission of the accelerated electrons is self-absorbed due to the strong magnetic fields …
The radio-loud AGN unification model associates powerful radio galaxies with radio-loud quasars and blazars. In analogy with the radio-quiet scheme, the nuclear regions of objects showing only narrow emission lines in their optical spectrum are thought to be obscured to our line-of-sight by a geometrically and optically thick dusty "torus". In objects showing broad emission lines we directly observe the innermost parsecs around the central black hole, i.e. the broad line region and the accretion disk. Radiation from the base of the relativistic jet dominates the overall emission of blazars, th…
We investigate the luminosity evolution of the host galaxies of radio-loud AGN through Hubble Space Telescope imaging of 72 BL Lac objects, including new STIS imaging of nine z > 0.6 BL Lacs. With their intrinsically low accretion rates and their strongly beamed jets, BL Lacs provide a unique opportunity to probe host galaxy evolution independent of the biases and ambiguities implicit in quasar studies. We find that the host galaxies of BL Lacs evolve strongly, consistent with passive evolution from a period of active star formation in the range 0.5 <~ z <~ 2.5, and inconsistent with either pa…
Based on the measured sizes of broad line region of the reverberation-mapping AGN sample, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift ($z > 0.5$) AGNs. First, using the archival $IUE/HST$ spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical relations between the BLR size and \Mg/\C emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mapping sample for calibration, two new relationships for determination of black hole mass with the f…
We have found empirically that the radio loudness of AGN can be understood as function of both the X-ray and optical luminosity. This way of considering the radio loudness was inspired by the hardness-intensity diagrams for X-ray binaries, in which objects follow a definite track with changes to their radio properties occurring in certain regions. We generalize the hardness-intensity diagram to a "disk-fraction luminosity diagram", which can be used to classify the accretion states both of X-ray binaries and of AGN. Using a sample of nearly 5000 SDSS quasars with ROSAT matches, we show that an…
We have studied the host galaxies of a sample of radio-loud AGN spanning more than four decades in the energy output of the nucleus. The core sample includes 40 low-power sources (BL Lac objects) and 22 high-power sources (radio-loud quasars) spanning the redshift range z~0.15 to z~0.5, all imaged with the high spatial resolution of HST. All of the sources are found to lie in luminous elliptical galaxies, which follow the Kormendy relation for normal ellipticals. A very shallow trend is detected between nuclear brightness (corrected for beaming) and host galaxy luminosity. Black hole masses ar…
An empirical relation between the broad line region (BLR) size and optical continuum luminosity is often adopted to estimate the BLR size and then the black hole mass of AGNs. However, optical luminosity may not be a good indicator of photoionizing luminosity for extremely radio-loud AGNs because the jets usually contribute significantly to the optical continuum. Therefore, the black hole masses derived for blazar-type AGNs with this method are probably overestimated. Here we first derived a tight empirical relation between the BLR size and the H$_β$ emission line luminosity, $R(\rm{light-days…
The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead of more interesting physical properties. Light from the centers of many AGN is obscured by optically thick circumnuclear matter and in radio-loud AGN, bipolar jets emanating from the nucleus emit light that is relativistically beamed along the jet axes. Understanding the origin and magnitude of radiation anisotropies in AGN allows us to unify different classes of AGN; that is, to identify each single, underlying AGN type t…
Gigahertz Peaked Spectrum (GPS) sources form a key element in the study of the onset and evolution of radio-loud AGN, since they are most likely the young counterparts of extended radio sources. Here we discuss space-VLBI observations of GPS sources, which enable us to obtain unprecedented angular resolution at frequencies near their spectral turnovers. Observed peak brightness temperatures of Log[T]=10.5-11 Kelvin indicate that synchrotron self absorption is responsible for their spectral turnovers. This is in close agreement with previous size - spectral turnover statistics for GPS sources. …
Low-luminosity AGNs are perceived to be radio loud and devoid of a ``big blue bump'', indicating a transition from a radiatively efficient, geometrically thin, accretion disc in high-luminosity AGNs, to a geometrically thick, radiatively inefficient accretion flow at low luminosities and accretion rates. I revisit the issue of the spectral energy distributions (SEDs) of low-luminosity AGNs using recently published, high-angular-resolution data at radio, UV, and X-ray wavelengths, for a sample of 13 nearby galaxies with LINER nuclei. I show that, contrary to common wisdom, low-luminosity AGNs h…
We review the latest attempts to determine the accretion geometry in radio-loud active galactic nuclei (AGN). These objects, which comprise ~10-20% of the AGN population, produce powerful collimated radio jets that can extend thousands of parsecs from the center of the host galaxy. Recent multiwavelength surveys have shown that radio-loudness is more common in low-luminosity AGN than in higher luminosity Seyfert galaxies or quasars. These low-luminosity AGN have small enough accretion rates that they are most likely accreting via a geometrically thick and radiatively inefficient accretion flow…
The spatial clustering amplitude (B_{gq}) is determined for a sample of 44 powerful AGN at z~0.2. No significant difference is detected in the richness of the cluster environments of the radio-loud and radio-quiet sub-samples, both of which typically inhabit environments as rich as Abell Class ~0. Comparison with radio luminosity-matched samples from Hill & Lilly (1991) and Wold et al. (2000a) suggests that there is no epoch-dependent change in environment richness out to at least z>=0.5 for either radio galaxies or radio quasars. Comparison with the APM cluster survey shows that, contrary to …
(abridged) We present a comprehensive study of a sample of 23 genuine radio-loud NLS1 galaxies which have the radio-loudness parameters greater than 100. The radio sources of the sample are ubiquitously compact. A significant fraction of these objects show interesting radio to X-ray properties that are unusual to most of the previously known radio-loud NLS1 AGN, but are reminiscent of blazars. These include flat radio spectra, large amplitude flux and spectral variability, compact VLBI cores, very high brightness temperatures derived from variability, enhanced optical emission in excess of the…
GPS and CSS radio sources are the objects of choice to investigate the evolution of young radio-loud AGN. Previous investigations, mainly based on number counts and source size distributions, indicate that GPS/CSS sources decrease significantly in radio power when evolving into old, extended objects. We suggest this is preceded by a period of increase in radio luminosity, which lasts as long as the radio source is confined within the core-radius of its host galaxy. We have selected a sample of nearby compact radio sources, unbiased by radio spectrum, to determine their radio luminosity functio…
We compare the host galaxies properties of BL Lac objects with those of radio loud quasars (RLQs) imaged by the WFPC2 on board of HST. The considered objects (z<0.5) are always well resolved and their host galaxies satisfactorily modelled by ellipticals. After homogeneous treatment of the data we find RLQs hosts are systematically more luminous (by ~0.7 mag) with respect to the hosts of BL Lacs. Using the M_BH - L_bulge relation, derived for nearby elliptical galaxies, we have evaluated the central black hole masses of our sample of active galaxies. These data are discussed in conjunction with…
We report accurate redshifts of 110 active galaxies (mostly radio-loud objects at z<0.4) observed in the course of a survey to find broad, double-peaked emission lines. These redshifts are measured from the narrow emission lines of these objects and are accurate to at least one part in 10^4 . For each object we determine a redshift from high- and low-ionization lines separately, as well as an average redshift from all the available lines. We find that in about 15% of cases, the low-ionization lines yield a slightly higher redshift than the high-ionization lines; the average redshift difference…
We used the widths of H$β$ and [OIII] emission lines to investigate the black hole--bulge relation in radio-loud AGNs, radio-quiet AGNs and NLS1s. The central black hole mass, $M_{bh}$, is estimated from the H$β$ line width and the optical luminosity, and the bulge velocity dispersion, $σ$, is directly from the width of [OIII] line. We found that the radio-quiet AGNs follow the established $M_{bh}-σ$ relationship in nearby inactive galaxies, while the radio-loud AGNs and NLS1s deviate from this relationship. There are two plausible interpretations for the deviation of radio-loud AGNs. One is t…
Hardness-intensity diagrams (HIDs) have been used with great success to study the accretion states and their connection to radio jets in X-ray binaries (XRBs). The analogy between XRBs and active galactic nuclei (AGN) suggests that similar diagrams may help to understand and identify accretion states in AGN and their connection to radio loudness. We construct ``disc-fraction luminosity diagrams'' (DFLDs) as a generalization of HIDs, which plot the intensity against the fraction of the disc contribution in the overall spectral energy distribution (SED). Using a sample of 4963 Sloan Digital Sky …
We present continuum observations of a small sample of high-redshift, radio-loud AGN (radio galaxies and quasars) aimed at the detection of thermal emission from dust. Seven AGN were observed with IRAM and SEST at 1.25mm; two of them, the radio galaxies 1243+036 ($z \sim 3.6$) and MG1019+0535 ($z \sim 2.8$) were also observed at 0.8mm with the JCMT submillimetre telescope. Additional VLA observations were obtained in order to derive the spectral shape of the synchrotron radiation of MG1019+0535 at high radio frequencies. MG1019+0535 and TX0211$-$122 were expected to contain a large amount of d…
We investigate the nature of the point-like optical ``cores'' that have been found in the centres of the host galaxies of a majority of radio galaxies by the Hubble Space Telescope. We examine the evidence that these optical cores are relativistically beamed, and look for differences in the behaviour of the cores found in radio galaxies of the two Fanaroff-Riley types. We also attempt to relate this behaviour to the properties of the optical nuclei in their highly beamed counterparts (the BL Lac objects and radio-loud quasars) as hypothesized by the simple Unified Scheme. Simple model-fitting …
The X-ray emission of radio-loud (RL) AGNs is a powerful tool for probing the structure of the accretion flow in these objects. We review recent spectral and variability studies of RL AGNs, which show that these systems have systematically different X-ray properties than their radio-quiet (RQ) counterparts. Specifically, RL AGNs have weaker and narrower Fe K lines and weaker Compton reflection components above 10 keV. The nuclear continuum of RL AGNs in the 2--10 keV band is well described by a power law with photon indices $\sim$ 1.8, similar to RQ AGNs of comparable X-ray luminosity. RL AGNs…
We use the ROSAT All-Sky Survey to study the X-ray properties of a sample of 625 groups and clusters of galaxies selected from the Sloan Digital Sky Survey. We stack clusters with similar velocity dispersions and investigate whether their average X-ray luminosities and surface brightness profiles vary with the radio activity level of their central galaxies. We find that at a given value of $σ$, clusters with a central radio AGN have more concentrated X-ray surface brightness profiles, larger central galaxy masses, and higher X-ray luminosities than clusters with radio-quiet central galaxies. T…
According to the currently accepted paradigm compact steep spectrum (CSS) sources are precursors of larger/older objects and gigahertz peaked spectrum (GPS) sources may be earlier stages of CSS sources. In this paper we confront this paradigm with the outcome of recent observations of CSS sources that are significantly weaker than those known before. In particular we claim that not all CSS sources must end up as large scale objects; if the activity phase of an AGN's central engine is shorter than the lifetime of a large scale radio source (up to ~10^8 years) the radio source associated with su…
We investigate the optical emission-line flux ratios of narrow-line regions, in order to determine whether the formation of AGN jets requires specific accretion conditions. We find that bright compact radio galaxies, which are powerful radio galaxies in the early stage of the jet activity, exhibit systematically larger flux ratios of [O{\sc i}]$λ$6300/[O{\sc iii}]$λ$5007 and smaller flux ratios of [O{\sc iii}]$λ$5007/[O{\sc iii}]$λ$4363 than radio-quiet (RQ) Seyfert 2 galaxies. Comparing the observed line ratios with photoionization models, it is found that the difference in the flux ratio of …
[ABRIDGED] We recently presented evidence of a connection between the brightness profiles of nearby early-type galaxies and the properties of the AGN they host. The radio loudness of the AGN appears to be univocally related to the host's brightness profile: radio-loud nuclei are only hosted by ``core'' galaxies while radio-quiet AGN are only found in ``power-law'' galaxies. We extend our analysis here to a sample of 42 nearby (V < 7000 km/s) Seyfert galaxies hosted by early-type galaxies. We used the available HST images to study their brightness profiles. Having excluded complex and highly nu…
We present the results of three ROSAT HRI observations of AGN expected to reside in clusters of galaxies. Although the exposures were truncated by the premature end of the ROSAT mission, valuable information could be achieved which greatly improved upon the previous PSPC results. For RGB 1745+398 we could separate the cluster emission from that of the BL Lac and could confirm the cluster parameters obtained from optical follow-up observations. In MRC 0625-536 the flux from the central point source contributes less than 3% to the total X-ray flux and the eastern component of the dumbbell galaxy…
The radio luminosity function (RLF) of radio galaxies and radio-loud quasars is often modelled as a broken power-law. The break luminosity is close to the dividing line between the two Fanaroff-Riley (FR) morphological classes for the large-scale radio structure of these objects. We use an analytical model for the luminosity and size evolution of FRII-type objects together with a simple prescription for FRI-type sources to construct the RLF. We postulate that all sources start out with an FRII-type morphology. Weaker jets subsequently disrupt within the quasi-constant density cores of their ho…
We have identified 7824 radio sources from the 1.4GHz NRAO VLA Sky Survey (NVSS) with galaxies brighter than K=12.75 mag. in the Second Incremental Data Release of the 6dF Galaxy Survey (6dFGS DR2). The resulting sample of redshifts and optical spectra for radio sources over an effective sky area of 7076 square degrees (about 17% of the celestial sphere) is the largest of its kind ever obtained. NVSS radio sources associated with galaxies in the 6dFGS span a redshift range 0.003<z<0.3 and have median z=0.043. Through visual examination of 6dF spectra we have identified the dominant mechanism f…
The majority of nearby radio-loud AGN are found in massive, old elliptical galaxies with weak emission lines. At high redshifts,however, most known radio AGN have strong emission lines. In this paper, we examine a subset of radio AGN with emission lines selected from the Sloan Digital Sky Survey. The probability for a nearby radio AGN to have emission lines is a strongly decreasing function of galaxy mass and an increasing function of radio luminosity above 10^25 W/Hz. Emission line and radio luminosities are correlated, but with large dispersion. At a given radio power, AGN with small black h…
We report the completion of a survey of radio-loud AGNs begun in an earlier paper, aimed finding and studying broad, double-peaked Balmer lines. We present Ha spectra of 13 broad-lined objects (3 with double-peaked Ha profiles). The final sample includes 106 radio-loud AGNs. 20% of the objects have Ha lines with double peaks or twin shoulders and of these, 60% can be fitted quite well with a model attributing the emission to a circular, relativistic, disk. We also compare the Hb and MgII profiles of 4 objects with models of photoionized accretion disks and find them to be in reasonable agreeme…
We highlight some of the principal results from our recent Hubble Space Telescope studies of quasars and radio galaxies. The hosts of these powerful AGN are normal massive ellipticals which lie on the region of the fundamental plane populated predominantly by massive ellipticals with boxy isophotes and distinct cores. The hosts of the radio-loud sources are on average 1.5 times brighter than their radio-quiet counterparts and appear to lie above a mass threshold of 4 x 10^11 solar masses. This suggests that black holes more massive than 5 x 10^8 solar masses are required to produce a powerful …
We present XMM-Newton observations of a complete sample of five archetypal young radio-loud AGN, also known Gigahertz Peaked Spectrum (GPS) sources. They are among the brightest and best studied GPS/CSO sources in the sky, with radio powers in the range L_{5GHz}=10^{43-44} erg/s and with 4 sources having measured kinematic ages of 570 to 3000 yrs. All sources are detected, and have 2-10 keV luminosities from 0.5 to 4.8x10^{44} erg/s. In comparison with the general population of radio galaxies, we find that: 1) GPS galaxies show a a range in absorption column densities similar to other radio ga…
Radio loud jetted sources with and without extended inner jet structure show good agreement with the simple ballistic ejection scenario proposed in the decreasing intrinsic redshift (DIR) model, where, because of projection effects, those that show the most obvious extended structure and large angular motions are assumed to have jets that lie close to the plane of the sky, and those with little or no structure and small angular motions are assumed to have jets that are coming almost directly towards us. This simple model also predicts several other relations seen in the raw data that, in some …
Blazars are currently separated into BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQ) based on the strength of their emission lines. This is done rather arbitrarily by defining a diagonal line in the Ca H&K break value -- equivalent width plane, following Marcha et al. We readdress this problem and put the classification scheme for blazars on firm physical grounds. We study ~100 blazars and radio galaxies from the Deep X-ray Radio Blazar Survey (DXRBS) and 2 Jy radio survey and find a significant bimodality for the narrow emission line [OIII] 5007. This suggests the presenc…
Recently, it was argued that the log(z)-m_{v} plot of 106,000 AGN galaxies could be interpreted as an evolutionary path followed by local AGN galaxies as they age. It was suggested that these objects are born as quasars with a high intrinsic redshift component that decreases with time. When the intrinsic component is large it causes them to be pushed above the standard candle line for brightest radio galaxies on a log(z)-m_{v} plot. In the jets of radio loud AGN galaxies, Beta_(app) is the apparent transverse velocity of the ejected material relative to the speed of light. In the cosmological …
